I have updated AF 3.5 to 4.2.5 and DNN from 3.2.2 to 4.9.5
I used the afimport utility that was supplied and the staging point of af 3.7.8

All seemed to go well and at the end the site operates well  and all forum groups/topics are upgraded.

The problem is that AF will not display for anyone except Superuser, I checked all permissions (DNN and AF) and all are as before. The only other way to access the forums is to set them as read/view/edit/create for All Users and set the page to All Users and it will display if you are NOT logged in but disappears again you login.

I've been going round in circles for a couple of days now and getting nowhere.

Update

OK I now have the Forum visible to my registered users (5 categories of user), The problem was that the DateLastActivity column was NULL for all users in the activeforums_UserProfiles table.
Not sure why this had not been migrated but an insert from a backup copy of the database has restored all my normal user access.

Anybody suggest what happened?